How Does a Chick Breathe Inside Its Shell?
Abstract Have you ever wondered how a chick breathes inside its shell? Every animal needs oxygen to survive, so the chick must get air somehow! Try this science project to discover the answer. Objective Determine if the pores in a chicken egg shell allow water to enter by soaking raw eggs in dye. Materials and Equipment *Measuring cup *Water *Large pot or bowl *Measuring teaspoon *Liquid dishwashing detergent *Blue food color *Store-bought raw eggs (6) *Tongs or large spoon *Cup *Plate or paper towel *Optional: Camera *Lab notebook Introduction Every animal requires oxygen to live. When animals, including humans, breathe in, oxygen enters the lungs, where it is shuttled into the blood stream and distributed to all the different parts of the body. The oxygen is used in an internal chemical reaction called metabolism to provide the animal with energy. The process of metabolism also produces a waste gas called carbon dioxide. In order to get rid of this waste gas, the blood stream carries the carbon dioxide back to the lungs where it is collected and finally breathed out. Animals that grow inside their mothers, like humans, get their oxygen from their mothers. The blood stream of the baby animal and the mother are connected through an umbilical cord, which allows the baby to collect oxygen that his or her mother breathes in and use the mother's lungs to get rid of the carbon dioxide. But how do animals that grow in a shell and do not have umbilical cords, like chickens, take in oxygen and get rid of carbon dioxide? Bird and reptile eggs have a hard shell. Directly under the shell are two membranes. When the eggs are laid by the mother, they are warmer than the air, and as they cool, the material inside the egg shrinks a little bit. This shrinking pulls the two membranes apart, leaving behind an air cell, also called an air sack, that is filled with oxygen. As the animal develops, it needs the oxygen replenished so it can continue to grow, and it needs the carbon dioxide it is making to be able to escape from the air cell. So, how does this happen? Well, if you examine a chicken egg carefully with a magnifying glass, you will see that there are tiny little holes, called pores, in the shell. A chicken egg shell has more than 7,000 pores! Do you think that the pores could be a way for carbon dioxide to escape and fresh air to get in? In this science project you will determine if substances can move in and out of an egg through these pores. To do this you will soak several raw chicken eggs in water with food color and detergent. Then you will crack the eggs open and look on the inside of their shells. If the pores really do allow materials to cross back and forth between the inside of the egg and the outside environment, then you should see dye on the inside of the shells. Ready to find out the answer? Time to dye some eggs! Terms and Concepts *Oxygen *Metabolism *Carbon dioxide *Umbilical cord *Shell *Air cell, also called an air sack *Pore Questions *Why do animals need oxygen? *Why do animals need to get rid of the carbon dioxide that their bodies make? *What are the different parts of a chicken egg? Variations *Do fresh eggs and aged eggs behave similarly? Buy a dozen eggs whose expiration date is at least two weeks away. Try this experiment with half of the eggs right away. Let the other six eggs age in the refrigerator for two weeks. Repeat the experiment with the aged eggs. How does the data compare between the fresh and the aged eggs? *Do other bird eggs give you similar results? Try it and find out! You can often find duck and quail eggs at Asian grocery stores. *If the pores in the shells of chicken eggs really do allow materials to cross back and forth between the inside of the egg and the outside environment, then when eggs are boiled in water the air inside the egg should be replaced by water, and water is heavier than air. You can test this by labeling and weighing several raw eggs, cooking them until they are "hard boiled," and then weighing them again. You will need to use a scale that can distinguish changes as small as 0.1 grams, such as a triple-beam balance (which your school may have) or a very accurate electronic kitchen scale. Did each egg gain weight? *For more interesting egg-based science fair projects, try Egg Substitutes. Photos Category:Zoology experiments